1. Field
The embodiments of the present disclosure relate to a thin film semiconductor device including a thin film transistor having improved electrical properties, an organic light-emitting display apparatus including the thin film transistor, and a method of manufacturing the thin film semiconductor device.
2. Description of the Related Art
Manufacturing costs can be reduced by manufacturing semiconductor devices using a semiconductor glass substrate, as compared to manufacturing semiconductor devices using semiconductor substrates. Accordingly, thin film semiconductor devices, such as flat panel display apparatuses, are being used in various fields.
An organic light-emitting display apparatus has high luminance, low operating voltages, and high contrast ratio because it is self-light-emitting. The organic light-emitting display apparatus may be implemented in ultrathin displays, and has a response time of about several microseconds (μs), such that moving pictures are stably reproduced. Also, the organic light-emitting display apparatus has a very wide viewing angle, is stable at low temperatures, and is driven at low DC voltages.
The organic light-emitting display apparatus includes thin film transistors to control light emission of pixels. A thin film transistor includes an active pattern formed by patterning a semiconductor material layer. The active pattern formed according to a patterning process known in the art has an angled edge portion. As a result, the electric field is concentrated at the angled edge portion, rather than at a center portion of the active pattern. Thus, a weak inversion occurs in the angled edge portion of the active pattern at a low voltage, and a parasitic transistor is formed. Accordingly, an unwanted hump phenomenon may occur in response to a drain current Id for a gate voltage Vg. The hump phenomenon occurring at the angled edge portion of the active pattern increases leakage current, and thus cut-off properties of a transistor may be degraded. Also, these issues may function as parametric deviation factors of a thin film transistor, thereby causing random smudges on a panel.